Guide pin cover for punch presses



Patented Nov. 27,A 1951 foFFlcE 2,576,112 p y l GUIDE PIN COVERFOR"SPUNCH`PRESSES Henry D. Gordon, Philadelphia, Pa.` Y

Application October 27, 1948, Serial No. 562718 1 v This inventionrelatesto guide pin vcovers -ior punch presses.

Punch and die presses-as devised for heavy *dieing and punchingoperations usually comprise 4'a fixed bed or Amivilgcar-rying'one dieo'r punch member, and amovable bed or platen carrying the complemental`die or'punch member. `=The movable `platen is 'arranged Afor verticalmovernents'between a position raised `vertically away from the4generally "l'lor-izontal anvil to vprovide clearanceior theinse'rifionland removal' of Work, and/a lowered positnjuxtaposed to theanvil, atevvhichrlatter the-punching or dieing pressure `isvtransmittedbytl'iecomplemental dies to the work. 'The Apressur'eiisapplied to 4the `plat'end'zvy suitable mechanical o r hydraulic`transmitting meansfroma source o'fpower, and is usually of a hghorderof magnitude. V-Punch `presses have 'varying capacities as 'to sizeandpressures used.

butall,` except possibly isome very `srnall presses,

'require the use of guide irods -`to maintain the `parallel'isrn ef' theplaten and anvil `during operations vonl the Work.l The guide rods *areof f such numbers -as toa'ccomplish the aligningiunction despitestresses and -tor-dues developed V'dur-ing contact of the platen withthe work. The `guide .pins, which Aare usually cylindrical "with more orless rounded Vfree ends, lare mounted onone of the relatively movablepress members andi-'exltend perpendicularly therefrom Itoward thecomplemental press member, andthe latter is apertured in alignment fwiththe respective guide pins lto receive 'the pins, and the apertures areusually provided withbiishings, whic'h'in many cases *exntndpartiallylfrom the `Surface of said complemental press membertowardthe pins. In some "cases :the clearance ibetween the punch membersat a `i?iaxirmim lis `coordinatedA with thele'ngth's off `the 'gu-ide-pinsso thatthe pins remain in the `bl-ishings at all times. In othercases, owing'to therequireinents of they press, theguide rods `have aclearance from `1thebushing entrance during `the greatest separationof'the relatively movable punclimembers. VIt is recognized that `the guidepin's'inu'st retaintheirexact alignment atall I times, normal to thepressing thrustoi the movable inem-ber, must-retain a coating oflubricant, mustbecontinuously free from rust and fric'tone creatingsurface conditions, such as nicks, scratches, "and "gouges, etc.

saryfattributes render the'guide rods and bush ings 'comparativelydelicate, so that `they must be housed: and protected againstimpacts-Tand must also besbfprotected vthat in the eventof clearance:between the-'endsofthefguide pins landltl'ieferids 'L 5 Claims. (Cl.F14-4612) ofthefalignedbushings, entry into `such lclearance-of`an'ycportions o'f the dperators lbody, =or "of Fthe `work, isprevented. This necessitates guards `having multiple `functions, i.e.protection "df the pins from impacts and also from thefrernova'lof.lubricant therefrom, `un'obtrusiven'ess 'and small size so' as-'notunduly to minimize 4the"spacene'c'e's- `sary toumanipulateithe Work,-p'ositiveV prevention Aof vthe entry of any `object over the ends" ofthe pins between the pins and the bushings, Whileat thesam'etimepossesse'dof follow-up functions for ifxnaintairring guarding atAall i times and in 'all relativeipositions of 'the pressy Without"imposing 'much appreciable Iload onrthe :presspower "1F1- nally', theguards 'must-be" simple in 'construction and attachment "to f the press.

\ Many attempts -f'havebeen 4made 'in the :past 'to -provide guards"having certain of' these `desired; characteristics, but fso far "as'known there has never before been provided any guard whichsuccessfully'providesfor' effectsl all of them. Prior art guards havetaken many fornis,=such"as sleeves .voi "canvas ror theilike` supported#by helical 'Wire springs, 'telescoping Yeup vassem'blies, "tc.,` andeach has failedftorfurnish lactual 'continuous Tguardi-ngunderadverseconditionsrand thuseach Fhas-leccano :more than va mere temporaryipaliative, 'or simu-lation of `artrue guard. This `is because each of"the Aprior 'art devices, so far'fas known, has possessed one or moreinherent and fundamental `undesirable features "'mi'litating aga-inst`universal satisfactory use.

. it islamongithe objects of this invention: "to provide -a *guard whichis "capable of iabsorb-ng lateral-shocks 'and `impacts Withoutinterfering with `or disturbingitsnoritinuous guarding functions; "toprovide `aguard `Which is readily inter- 1changeable"from 'onepinto'another pin, and from onecdie "set to "another" die set; to Iprovide aguardhavingpredeterminedly the ability 'to establishand maintain 'all of:theeuardingiunc- `tionsrecitedabove as essential; toi provide fa guardwhich obviatesf't-he '-di'sadvanta'gesof vprior guards; rto provide faguar'cl of extremely long life; `to provide a guard of simplicity landease o' i-ormation; to provide a guard which resists bend-s'ordistortiona and which Aeven if dented will continue Tto fun'ctio'nffor guarding purposes; :to providera fguard'form'ed "of `a single`integral Ielementp to provide a `guard of such simplicity Canduniversality 'loi "application `as to "be 'readily carried infa fewstock sizes `and Witnagreatree 'detionin measuring 'and 'fitting asrequired by prior art devices; to'provide 'aguard "which 'isiconstantly. seliecentering sci :inhat` :despite teniembodiment; I1Fig.3 represents a fragmentary enlarged section Ythrough the guard inguarding relation'beporary conditions of asymmetry during use, as

cant on said pins and the prevention of rust and surface interruptionssuch as nicks, scratches.

and the like, on the guide pins; and to provide 1 Fig. 1 represents askeleton perspective of Va typical punch-press assembly, showing thelocation of the guards of this invention in guarding Arelationto guidepins. `extending between the movable platen and the fixed bed of thepress; 1".:Fig 2 represents `a side elevation of the guard of thisinvention in a preferred but illustrative Vtween the press elements andrelative to an illusti-ative'pin and bushing assembly, with the latterlshown'in dotted lines;

;'Fig.'.r,4 Shows a guard in an illustrative com- ;pressedshortenedvcondition at the bottom of the :stroke of thelmovable platen toward thefixed -bed, with the telescoped relation of the pin and .bushingindicated in dotted lines;

Fig. 5 represents a-.topplanof the guard;

Fig.: '6 represents.a-fragmentarysection of a modified form ofspring'guard in which the initial Y yyield in response to axialcompression is from the an upper position, as illustrated in Fig. 1, anda ilower punching or pressing position on work, (not shown) disposedbetween the press or die members I Il and I I von one sideand themovable platen I-2 'on the other. Platen I2, of course, may also fcarryadie member, but in the interests of clarity 'thishas been omitted fromthe showing of Fig. l.

Illustratively, the rigid guide pin I3 is mounted -on'the fixed anvil orbed member I0, and extends perpendicularly therefrom toward the movableplaten I2as the guide pin to be guarded. The upper endl of the pin I3 ischampfered or slightly rounded in a guiding free end or terminus I4,

and 'the yplaten I2 carries a bushing I5 having aconcentric bore I1 inalignment with the pin.

V,The guide pin has sliding guided engagement in .and relative to thebore of the bushing. Usually the bushing vI5 has a lower extension I6extending out Vof the plane of the platen toward the 'fixed bed.Usually, also; in the initial open disposition of fthe press with theplaten I2 in its raisedposition away fromV the bed I0 there is avertical clearance I8 between the end I4 of the LpinyI3x-and the lowerend IB of the bushing. Manyyserious' mishaps have been occasioned .by`Vthe` inadvertent interposition of an operators 4'l1and,.or,a heavyandrigid piece of Work, insaid 4 clearance I8, maintained as the platen I2starts downward on its punching or dieing stroke.

The guard 20 for the pin and bushing assembly thus described inaccordance with an illustrative but presently preferred embodiment,comprises a ribbon of metal 2I wound upon itself in the form of a spiraleither of actually contacting walls, or of slightly spaced walls tominimize friction, drawn out axially to form a helix comprising inprofile a substantial truncated hollow cone, having arelativelylargeend'22 and a relatively small end 23. 'Ihe walls of thecone comprise at any point a ribbon lying generally and preferablyalmost exactly parallel to the axis of the cone, and each portion of theribbon overlaps a` portion of the adjacent ribbon in the extended helix,so that each yportion of the ribbon is backed-up,'so to speak, by thenext adjacent turn of ribbon.Y Illustratively, the ribbon may have but afew thousandthsof thickness but transversely may be of the order of 1%inches, which, of course, may be greater or smaller than thisillustrative form, depending upon the differentials between the maximumand minimum clearances between the press members and the thickness ofVthe ribbon, and the overlap is preferably, although ymerelyillustratively, of the order of ,somethingV less than one-half of thelateral width of the ribbon. As the ribbon in top plan is a spiral, allAof the turns at any intersecting axial radial plane are substantiallyparallel to eachother, In the preferred form the turns are in lightlytouching contact, although for the elimination of friction each turn, asnoted, can be spaced a slight distance from each adjacent turn, if thisshould be preferred. v

The guardas described is preferably made of -tool steel alloy in theillustrative embodiment, and not of so-called springV steel, and whenproperly formed itis tempered to have the desired resilience. Theadvantage of the tool steel is inits seeming immunity to crystallizationunder repeated deforming stresses, as contrasted with spring steel,although the latter material, of course, may be used, especially forcertain small sizes of guards. Y f

.The truncated cone formed of the overlapping substantially parallelturns, each generally parallelV to the axis` of the cone, has the largeend 22 of such diameter as to flt fairly freely about the extended endI6 of the bushing, to generally cen'- ter the upper or large end of theguard. The

smaller end 23 is preferably of such size as to have .afairly free litover `and about the pin I3 at the base thereof. In order to assemble theguard and the pin and bushing assembly, the guard is compressed axiallyinto a small compass, which usu- ,ally can be effected with mere manualmanipulations, and inserted laterally into the space I 8 and permittedto expand in both directions so that the large end surrounds the bushingand the small end expands axially of and surrounds the pin I3. Theinitial loading of the spring is such that when installed and with thepress open toits fullest extent, the ends 22 and 23 of the guard axiallyabut the respective parallel surfaces of the press elements adjacent tothe bushing rand pin respectively.- There isno necessity for greaterloading than this, v

lIt will be observed that the light resilient abutment ofthe ends 22andV 23 against the respective parallel surfaces of the press elementsadjacent to the pin and bushing respectively is the only attachment ofthe guard to the press and this atlahmelll 11SV oating. This is. themajor factor in ,ritmica 11th-eiself-aiigr'mient of' theaguard.thevslight transverse l clearance foftheirespectivefendsioi Vthe `guard`relative "to '.the -faligned complemental .pin aand,.bushingieleinenisshown,iwhichfisiillustrative or `a preferred 4:wider clearance., is;adeguate to secure two inmortant functions `:in Iseli-alignment`pursuantto zanytransverse; impact for estreSS against theguardaatanyangle-of thetperiph uery fof theaguard, and :regardless :of theelocation'oftheriocal .point ror ffocal area `of fthe, del-'ormi-ng impactprrstressaxially-of sthegu ard.

'l "To :assist in-1,understanding-)thisffunctioning, will be seen thatas thebushingffl'islarger -in diameter vthan'the pin l 3 an imaginarytruncated y c onefexists` betweenthe outer terminal -end of .thercushingaandthe pin :adjacentto the surface Ain *which it `isrnounted,the fangle Tof ,-thesides `of nwhich'fto Lthe axis becomermoreobtuse thepress members `move `from vfully a separated to` fully closed. i Thereis therefore at `any instant tan imaginary line Vbetween `-t-he bushing:and 4the -pin `having` an anglewiththe axis of .the assembly.

l -TIi-he :first Vresult of` 1the applicationcf lateral force ,to `aside of :the lguard islto cause the entire guard'fto move transversely,in yielding to 4the force in the line of the force, by transversesliding Yor iioating of the respective ends -on--the respec-.tiveparallel flat faces-of thepress, until the large `end internallyengages and `stops against the external periphery fof the bushing in a`generally axial line, area, or point nof mutual contact, l,and thesmall end slides oriloats transversely on--the flat surface upon which:it abuts untilV it vinternal-ly `-engages `andstops against the external`surfacefof ,the `pin in ,'algenerally-axial line or` area` of mutualcontact, which respectivey Vareasfoaf mutual `contact are Vin general:axial alignment 4with-each other and with -the resultant forcelbeinglexerted against the guard. ,'Ifhis-causes-the guard :to :move initiallyinto La `position with its axis ,generally asymmetrical -or` eccentric`of the axis of .the pin and `bushing assembly, Tbringing `the impactside .of the-conical guard `into such-close general -pare allelism withthe contiguous side `of .the imaginary cone asto `be practicallycoincident therewith; At the'same timefof-.coursa lthe side-fdiametrically opposite tothe impact will .have moved Vfurther away`from the oppositefside-of .the imaginary cone. Continuation Vof rthelateral thrust causes the impact side .of Athe coneguard to yield generrallyrconcavely .in bridging relation between the pointsor areasof mutualcontact. This increases the degree-of overlap of `adjacent turns onltheimpactside, .toincrease `the strength of the cone. and as .the impactside is then closer to the axis of, the Apin than is the opposite,.side, the distortion `into `concavity is stopped `by the impingementof ,the inner surface of the guard against" the closely adjacent sideof' the pin, with Va merely shallow concavity. The thrust .or force isthen "6 :andbuiingrespectivelm thejcon'vexlsdistortinnds .spread over`iliezentire llength of the-guardand :although the :turns non :this:side are :thus pulled iunequally outzof Atheir initial overlappingrelation, '.theyareinot separated, and eachretains fthe same a generalperipheral 'curvature` as the` adje cent turnsand is iree Ito distributethe distortion inlaccordance with ther-inherent properties'ofthe Iunit.It will be seen that under certain :condi-,- tions "the disturbingtransverse `force mayberso applied that `the generally `planar endsofthe aunitmay `til-t ,slightlylon the respective faces whichV `they abut,about the fedges of `the `ends .iopposite totheareas of mutualcontactmentioned as ipivots, `and this temporary situation iszpermitted`by theiloating abutment provided, `dur-- ing which the impactsideslofthe end turnsmay slide slightly axially of the unit onthelrespectivebushing and pin;

When 'the `press `comes together during the ape plication of thetransversev stress thedistorted but `relatively aligned turns are forcedtogether in lself-alignment. As a corollary thereto, the 'succes'sively:wider turns, in descending, engage the object, causing the distortion,or producing `the Ydisturbing force, and convert the lateral -orradial"force into a generally axial resultant force -Apassing'harmlessly down along the side of ythe guard. l "The ability of theopen ends to floa-tlin abutment `against the parallel surfaces as the`only attachment of the guard not only provides the 'self-alignment andreturn to `general concentric ity-of the guard to the pin and bushingassembly, :but also permits free rctationvof either or both endsthereoffwithoutsgrooving the `faces as torque lis developed on the turns of thecoiled deviceiby reasonof the closing and opening of thenpress, andfurther without unlapping of the turns rvas would follow anchoredattachment of eitherfor both ends.

The Width oflthe ribbon is preferably predeter# -mined toube'islightlyless than the-minimum clearance of the bushing-extension I6 relative `tothe `surfaceoi the fixed Abed surroundingthepin 13, so `that whenwthepress is actuated to compress the -guard `axially, the approach o'f thebushing relatively to the fixed bed will be ineffectual-Lto crush anyturns of the guard that may beuaxially -disposedbetween said endandsaidfix'edbed.

vlit -will be observed that the resilient `metal -guardforms asubstantially complete enclosure forthe pin and bushing for whichpurpose both open Vends -fengage the press surfaces which theyiabutunder the light loading necessary to self sustain the unit `with theperipheral rims or edgesof vthe end turn or turns of both endsinsubstantialplanes for l'at least the major periph- `eryiofssaid ends, asshown in'Figs. 2 and 3,has such reiniorcedstrength by 1the overlapping"areas of `,the:respective iturns as to be ableto withstand DDGSS.

litt.` Iwill ibe :seen that with` equal overlap and equaliwidths' of.ribbonthroughout the spring,`be. causexof the `differential lradii of:the turns,A 'the application `of axial `pressure ."to `the guard willcausezthefucollapsezoiitheguard :from lthe large 'end-.rrstsJnf'mosticasesithis istsatisfactory` asthe clearancesV wilkbesuchfthatitmay noti-nake diffterence.` However; from.time,totimetherefaresitualisrinwhichnbecausefofasmall clearancestor relatdiproblems, itishighly desirablef'tha't the collapse under axial pressure vbe from thesmall endf'iirshor evenbe simultaneously' from both ends for a limitedtravel of the platen relative to thefanViLIWith the mid-portionthe `lastportion of'xthespring to be compressed. It is a feature ofthis inventionto provide selective'guard telescoping or collapse under stress againstthe resilience of the whole, whereby as desired the large end,orthesmall end respectively vis compressed or' collapsed first,accordingto the predetermination`- thereof.- If it is desired to havethe device yield substantially similarly from both ends, the spacingcrrelative'overlap of the guard turns is changedpfromithe substantiallysimilar overlap described; `into one in which, starting with thesmalleraend of the guard, the turns have progressively different degreesof overlap, by'becoming smaller in overlap and greater in depth ofunoverlapped turns as the helix. is woundA toward the Itop turn, or endof the guard, whilestill retalningthe same width or thickness of ribbonthroughout the length. lIf it is desired to have the smally end collapsetoward the larger end, this isiaccomplished by Ahavingthe turns ofribbon from which the-helix is formed contain progressively morematerial in turn as the vribbon moves from Vthe lsmall end toward thelarge end., This maybeaccomplished in an expensive'way according Vtopresent production methods by having the ribbon of the same width butpossessed of progressively changing thickness, increasing from vthesmallyend toward the large end. It is preferred, however, to secure thedesired small end initial collapse or yield by-providing a ribbon ofvarying width, say, in an'illustrative caseone and one-,quarter inch'for the top large turns, progressing downwardly in width to one inch atthe -small end. This yisaccompanied in the winding of the helix Ibyprogressively changing the proportion of overlap of the adjacent turns.Y

A's-shown in Fig. 6, for instance, the upper turn 24V-is of the Vmaximumribbon width, and it, has, a small overlapon and about the next adjacentturn -25,V which is, of course, of `slightly smaller width. VIn turnthis turn 25 has a slightly greater percentage of overlap on and aboutthe third turn A26, but this latter turn is of still smaller width. TheVfinal small turns 2l and 28 of the Vnarro'west ribbon have the largestpercentage of overlap, i.`I e. the smallest depth of exposed turn. Bysuch structure, axial pressure finds the upper larger turns mostresistant to distortion, and the smallest turns most easily -distortedin forming the helix into a compressed substantial spiral. The advantageof such selectability will be clear. Having thus described my invention,I claim:

`v1. InV combination, a rst and a second press Y memberymeans mountingthe respective members for relative movement between open and closedposition, a bushing mounted in a smooth surface of the rst member, a.guide pin mounted in a smooth surface of the second member complementalto said bushing, a guard unit for the bushing and pincomprising in itsentirety a lightly loaded ribbon of resilient metal coiled upon itselfto define a hollow truncated cone with adjacent turns in overlappingrelation and having respectively large and small open ends, the unit inexpansion abutting said respective smooth surfaces and beingself-sustaining whereby the vlarge endsurrounds said bushing in aYlimited floating on said surface of the nrst membenand the small endsurrounds the pin in a limited floating on said surface. of the secondmember, whereby in response@ to generally radial lateral-pressure on'the 1un'itfthelarge end internally abuts the bush'- -tire length oftheunit with maintenance of overlap and a conformation of each turn to thesame general peripheral contour of adjacent turns of the unit,whereby'the 'unit self-'aligning on the powerstrolzev of the press. fL2. In presses, cooperating complemental separable press members, aleader pin mounted on one membena bushing complementalto therpin mountedon the other member, each member having Ya 'surface immediatelyadjacent'tothe respective mounted pin or bushing which is smooth-andotherwise uninterrupted, a guard comprising in'its entirety a ribbonofk metal -wound into V,coiledfforrndefining' a truncated hollowopenended cone with adjacent 'turns in at least partialoverlappingr'elation, and having such lightloading Ain 'resiliency' asmerely to self-sustain the guard in limited floating abutment of theopen ends Vthereof VVagainst the respective smooth surfaces as thev onlyattachment of the guard, without Vconsuming appreciableV press power,the said open ends being of such diameter as to surround respectivelythe pinv and bushing with a clearance, said g'ua'rdvbeing disposed forlateral yielding' in response to lateral force thereon to engage smallareas internally of the end turns against the pin and bushing and tobridge* the pin and bushing on the thrust' side with increase of overlapof some turnsaccompanied by `distortion on the other sidepfthe guard inwhichthe overlap decreases unequally without separation of adjacentturns as the thrust-induced distortion is spread along the length'of'theguard with maintenance of substantially the-same general peripheralcontour of adjacent tr'ns as 'they endturns float on said surfacesy withrelation to the respective pin and bushing yand 4to said respectivesmall areas.

3. Af 'guard for operative association with' a leader pin andcomplemental bushing of known diameters of a press of known clearancehaving substantially smooth and otherwise uninterruptedsurfacesimmediately adjacent to the respective bushing and pin, comprising inits entirety a single piece of metal in ribbon form wound upon itselftodene a Yhollow open-ended truncated cone of light loading such. thatwhen freely expanded it is [slightly longer than such clearance,theresp'ectiv'eend turns of said cone being predeterminedly, of adiameter greater than such resp'ectiveV pin and bushing and the edgesthereof being relatively smooth such as to abuttingly engage l.suchsmooth surfaces with a relatively small lateral clearance from therespective bushing and pin so thatcpart" at least of said end turnsfloat relativeto such bushing and pin on said surfaces as the soleattachment of said guard, whereby in -response Vto lateral forcesagainst said guard and internal abutmentthereof against such respectivebushing and pin the guard opposite to the force can distribute thedistortion throughout the-length of the" guard with maintenance ofoverlap' `ofand the same general peripheral contoursof adjacent turnswhereby the guard `is alwaysselfzaligning, 4. A guardi as recited in'claim"3, characterized byla': progressive change in lead per turnwhereby the small end of the guard collapses rst under axialcompression.

5. A guard as recited in claim 3, characterized by a progressive changein the metal volume per unit of length throughout the major length ofthe ribbon decreasing from the large end thereof. whereby the small endof the guard collapses first under axial compression.

HENRY D. GORDON.

10 REFERENCES CITED The following references are of record in the fileof this patent:

UNITED STATES PATENTS Number Name Date 89,945 Rohrbeck May 11, 18692,141,027 Weisman Dec. 20, 1938 2,320,240 Janiszewski May 25, 1943

